Saw blade sharpening machine

ABSTRACT

A grinding machine is designed as a multi-station grinding machine, which has two complete grinding stations. The grinding stations have grinding heads, which can be moved by means of appropriate positioning devices, for example compound table arrangements, and/or pivot tables, in relation to the saw blade. Positioning devices and arresting devices for the workpiece are furthermore parts of the grinding stations. The workpiece support is used for positioning the saw blades to the extent that their center axis is to be fixed in the grinding. The rotation of the saw blades around this center axis M, and the clamping in place of the saw blade in the respective rotated position for performing the grinding operation is the task of the respective units in the grinding stations.  
     A very rapid and precise, and therefore cost-effective, processing of saw blades is possible by means of a grinding machine designed in this way. The grinding machine is particularly suited for sharpening saw blades in the course of their manufacture.

[0001] The invention relates to a grinding machine, in particular for sharpening saw blades in the course of their manufacture.

[0002] Saw blade sharpening machines are known which have one or several grinding heads, by means of which the teeth of a saw blade are to be brought into the desired shape. It is known that several grinding heads are required or used for this. For example, grinding heads are known which have a first grinding disk, for example for the tooth back, and a second grinding disk, for example for the tooth face. It is then necessary to process, for example, first the tooth back and then the tooth face of a saw blade tooth by tooth. The saw blade is rotated on by exactly one tooth after each grinding process of a tooth by means of an appropriate positioning device. The time required for processing the saw blade then is the time required for two circulations of the saw blade. This can be shortened, if separate grinding heads are provided for the tooth face and the tooth back. However, this has the disadvantage that it is necessary to match the working of both grinding heads exactly, i.e. to synchronize them. When the saw blade is moved on, both grinding heads must be out of engagement with the respective tooth.

[0003] Based on this it is the object of the invention to create a saw blade sharpening machine which is suitable for generating a large output, in particular regarding production.

[0004] The grinding machine in accordance with the invention has a workpiece support which is arranged for the simultaneous reception of several identical workpieces, in particular saw blades. The workpiece support can be moved by means of a positioning unit in such a way that a received workpiece (saw blade) sequentially passes through at least two grinding stations. At least one grinding device, one positioning device and one arresting device are provided in each grinding station. The positioning device and the arresting device, which are used for the stepped rotation of the saw blade or other workpiece, as well as for clamping it in place in the processing position, are assigned to the respective grinding station. Therefore the positioning and clamping of the workpiece (saw blade) is a task of the respective grinding station. By means of this it is possible to attain high clock rates without the grinding stations interfering with each other.

[0005] Only one grinding device operates at any given time on each saw blade. It is therefore not necessary to synchronize the grinding processes on different surfaces of the individual teeth. Only the total processing time in each processing station must be synchronized, so that the workpiece support as a whole is moved on when each of the two processing stations is finished. But it is possible to let both grinding stations operate unsynchronized with each other. This provides the option, for example in connection with saw blades with offset teeth, to process the right and left flank alternatingly, but also every tooth back.

[0006] The positioning and the arresting device for the workpieces takes place by means of the grinding station. This has the further advantage that the accuracy of the result of the work depends only to a slight degree on the accuracy of the position of the workpiece support. A high manufacturing quality can be achieved in a simple and cost-effective manner.

[0007] In addition, it is possible to minimize nonproductive time by means of the grinding machine in accordance with the invention. This is successful if every grinding station is assigned the processing of only one surface, or group of surfaces of all sawteeth. For example, one grinding station can be equipped to process the tooth back, and the other grinding station to process the tooth flanks. In many cases it is possible to omit processing the tooth face.

[0008] If each of the grinding heads only needs to process one surface, or group of surfaces, the movements of the grinding heads can be reduced to merely feed motions. Position changes, such as are required when one grinding head is intended to process a tooth face, as well as tooth backs, or tooth backs and tooth flanks, can be avoided. This has a time-saving effect.

[0009] With the above mentioned concept, one grinding station processes only the tooth backs of a saw blade, for example, while the other grinding station only processes the tooth flanks, for example. In comparison with grinding machines in which processing of the tooth flanks and the tooth backs of the same saw blade takes place simultaneously, it is possible to even increase the output.

[0010] Processing of the respective tooth surfaces is preferably performed with only one grinding head which contains only one rotary driven grinding disk. The shape of the grinding disk is arranged to correspond to the shape of the surface to be processed. To this extent the grinding head is preferably specialized, position changes, and therefore corresponding positioning times, such as they were common with grinding heads having several grinding bodies, are in principle avoided.

[0011] If necessary, a grinding head can also be provided with a grinding finger, for example for creating a hollow face.

[0012] A twin grinding head can also be provided, in particular for processing tooth flanks. It is preferably designed in such a way that two driven grinding bodies (grinding disks) can be simultaneously brought into engagement with the oppositely located flanks of one tooth. A considerable advantage of this step lies in that the tooth flanks of a saw blade can be ground in one passage of all teeth of the saw blade, so that the same grinding time results as a whole, as that used for processing the tooth backs in the other grinding machine. Two grinding heads, which can be moved (away from and toward each other), are part of the twin grinding head, one of which is for example located above, and the other for example below the saw blade. The relative movement of the grinding heads in respect to each other can be achieved by means of linear guide devices and corresponding drive mechanisms, for example. Displacement of the grinding heads in the radial direction of the saw blade can be accomplished by the displacement of a common support. The same applies for the circumferential direction and possible pivoting movements.

[0013] The grinding machine in accordance with the invention is suitable for sharpening saw blades with hard alloy inserts, particularly in its embodiments with twin grinding heads in one processing station. To produce saw blades equipped with hard alloy it is possible to provide a soldering station in place of or in addition to a grinding station, which is used for providing the saw blades with hard alloy bodies on the teeth.

[0014] In connection with the grinding machine of the invention, the grinding stations are not only assigned the processing of the workpiece, but also its positioning. But the workpiece support is merely used for conveying the workpieces from one grinding station to the other. Accordingly, each of the grinding stations can have frames supporting the processing device, the positioning device and the arresting device. The grinding machine can be provided with a base frame which supports the positioning unit for workpiece supports, as well as the two frames of the processing units. Demands made on the machine frame are in this case also relatively low in cases where it is intended to achieve a high grinding accuracy of the workpieces (saw blades).

[0015] The grinding heads of the grinding stations are seated by means of guidance devices and displacement devices in such a way that they can be displaced in several directions and are preferably also pivotable. By means of this the setting of the grinding heads into a base position and, starting from the latter, a feed position, is made possible, which is repeated at each sawtooth and is required for performing the grinding process. But the assumption of the base position is only used for the initial positioning and set-up of the grinding station in regard to a defined saw blade.

[0016] Preferably the saw blades are seated in a freely rotatable manner on the workpiece supports. Appropriate receivers, for example mandrels or the like, are used for this. The mandrels can be provided in predetermined positions on the workpiece supports. It is also possible to preset several positions for each mandrel to match different saw blades to be produced. Preferably the predetermined positions are arranged on the arms of the workpiece support in such a way that the teeth of the respectively assigned saw blades are positioned in the same grinding position.

[0017] Further details of advantageous embodiments of the invention ensue from the drawings, the description or further dependent claims.

[0018] An exemplary embodiment of the invention is illustrated in the drawings. Shown are in:

[0019]FIG. 1, a grinding machine in accordance with the invention in a perspective view,

[0020]FIG. 2, the grinding machine in FIG. 1 in a schematic view from above,

[0021]FIGS. 3 and 4, a portion of a saw blade in an enlarged perspective representation, and

[0022]FIG. 5, a workpiece support in a partial perspective plan view.

[0023] A grinding machine 1 is illustrated in FIG. 1, which is preferably employed for grinding saw blades 2 in the course of the manufacturing process. The saw blades 2 are saw blades equipped with hard alloy, as they are schematically indicated in FIGS. 3 and 4 on a different scale and in part. Each tooth 3 of the saw blade 2 is provided with a hard alloy body 4, which projects over at least one of the flat sides of the saw blade 2 in the axial direction, and which protrudes above the tooth in the radial direction, which can be seen in particular in FIG. 4.

[0024] The hard alloy body 4 is substantially embodied as a cube, wherein its radially outward pointing surface defines a tooth back 5, and its two lateral surfaces pointing in the axial direction define tooth flanks 6, 7. With its front, the hard alloy body 4 defines a tooth face 8 on the front of the tooth 2.

[0025] Even in connection with the production of cost-efficient saw blades it is necessary to grind the tooth back 5 and the tooth flanks 6, 7. However, in many cases it is possible to omit grinding the tooth face 8.

[0026] With the grinding machine 1 in accordance with the invention, grinding of the tooth back and grinding of the tooth flanks takes place in grinding stations 11, 12, which are separated from each other and through which the saw blade 2 passes sequentially. Here, a workpiece support 14 is used for transporting the saw blades, which has three arms 15, 16, 17 arranged at equal angular distances from each other, such as can be seen in the view from above in FIG. 2, for example. The workpiece support 14 is rotatably seated around a vertical axis of rotation 18. A positioning unit 19 is used for moving the workpiece support 14 on by respectively 120° around this axis, which moves the workpiece support 14 forward and then, during the processing of the saw blades 2, maintains it in the position reached.

[0027] The workpiece support 14 and its arm 15 can be seen in FIG. 5. Like the other arms 16, 17, the arm 15 extends away from the axis of rotation 18 in the radial direction. The arms 15, 16, 17 are embodied essentially flat on the top. A mandrel 22 is used for example as a receiver for the saw blade 2, which has on its upper end a tapering, for example conical, section 23, underneath that a flange 24 for seating the saw blade 2, and a screw thread-equipped shaft 25 for connecting it with the workpiece support 14. One or several openings 26, 27 provided in the arm 15 are assigned to the mandrel 22.

[0028] The mandrel 22 and the openings 26, 27 are oriented in such a way that the center axis 28 of the mandrel 22 is oriented parallel in respect to the axis of rotation 18. Therefore the saw blades 2 are horizontally oriented in the grinding machine 1, as seen in FIG. 1, and rest, centered by the mandrel 22 but rotatable, on the respective receivers 21. It is also possible to provide another receiver, which holds and seats the saw blade, instead of the mandrel 22.

[0029] As can be seen from FIGS. 1 and 2, the processing stations 11, 12 are similarly designed. Each has a mounting, or a frame 31, 32, on which a table 33, 34 is pivotably seated. A drive mechanism, not further represented, is assigned to the table 33, 34 in order to be able to bring the table into a desired pivoted position.

[0030] As illustrated in FIG. 1, each table 33, 34 supports a compound table arrangement 35, 36 which, in turn, supports one grinding head 37, or two grinding heads 38, 39.

[0031] Together with the compound table arrangement 35, to which drive mechanisms, not further represented, are assigned, and the grinding head 37, the table 33 constitutes a grinding device 41. The table 34, together with the compound table arrangement 36 and the grinding heads 38, 39, also constitutes a grinding device 42.

[0032] The table 33 can be displaced around a vertical pivot axis 43, which is parallel with the axis of rotation 18. This axis is also called the B axis. A first carriage of the compound table arrangement 35 can be displaced radially in respect to this in the Z direction. This Z carriage supports a carriage which can be displaced transversely to it (X direction). In turn, the X carriage supports a carriage which can be displaced in a direction parallel with the axis of rotation 18 (Y direction). The displacement directions X, Y, Z, as well as the B axis are used for setting up and adjusting a desired position of the grinding head 37, as well as for performing a feed movement of the latter. It is alternatively possible to determine the sequence of the carriages in a different way.

[0033] The grinding head 37 has a driven grinding disk 44, which is designed as a grinding disk for the tooth back 5. It operates by means of its narrow exterior circumferential surface. It axis of rotation is oriented approximately radially in respect to the saw blade 2 and matches the direction of the tooth back 5.

[0034] The processing station 12 is correspondingly laid out. The table 34 is pivotable around a pivot axis 45, which is aligned parallel with the axis of rotation 18 and is called the B axis. A carriage can be displaced in the Z direction radially in respect to the B axis on the table 34. In turn, the Z carriage supports a carriage which can be displaced horizontally transversely to it in the X direction. It is provided with two carriages (Y1, Y2), which can be separately displaced in the Y direction, each of which supports a grinding head 38, or 39. Each of the grinding heads 38, 39 has a grinding disk 46, 47 used for grinding the tooth flanks 6, 7. Their axes of rotation are oriented parallel with each other, as well as approximately radially in relation to the saw blade 2.

[0035] The two frames 31, 32 are seated on a common machine frame, or base frame 48, which also supports the positioning unit 19. A positioning device 51, 52, as well as an arresting device 53, 54, are respectively provided for each processing station 11, 12 on the base frame 48, or the frames 31, 32 or, as illustrated in FIG. 1, on the tables 33, 34. The positioning devices 51, 52 are constructed in the same way. They are embodied as so-called separating fingers, which have a pin 55 supported by a finger and used for moving the individual teeth 3 of the saw blade 2 in steps. In the course of this, the pin 55 moves in a loop-shaped path 56. The respective separating finger operates synchronously in respect to the grinding head 37, or the grinding heads 38, 39, in each processing station 11, 12.

[0036] The arresting devices 53, 54 are also embodied identically with each other. The arresting device 53 is designed as a clamping device and is used to firmly clamp the saw blade 2 in the processing position in such a way that its tooth 3 is maintained fixedly and steadily during the grinding process. To accomplish this, the arresting device 53 has two clamping jaws, which are arranged opposite each other and extend above, or below the saw blade 2 and come into contact with its flat sides. The lower clamping jaw 57 is preferably stationarily arranged, while the upper clamping jaw 58 is seated in the form of a rocker above the lower clamping jaw 57, which can be seen in particular in FIG. 1. An appropriate drive mechanism 58, which acts on the rear end 59 which is remote from the saw blade 2 of the upper clamping jaw 58 a, is used to firmly clamp the saw blade 2 between the facing clamping jaws, or release it, in a controlled manner.

[0037] As FIG. 2 further shows, the processing stations 11, 12 are arranged offset from each other by 120° in respect to the axis of rotation 18. A position arranged between them, also offset by 120°, is the loading and unloading position. A loading and unloading unit 61, whose basic principles at least can be seen in FIG. 2, is provided on the grinding machine 1 for removing ground saw blades from the workpiece support 14 and to place saw blades on it which still must be ground. One or several saw blade supports 62, to which a gripper 63 with vacuum suction devices and/or magnets is assigned, can be part of it. The gripper can be maintained on a carriage 64, which is seated to be linearly displaceable and which causes the loading and unloading of the workpiece support 14.

[0038] The grinding machine 1 so far described operates as follows:

[0039] During operation, the gripper 63 initially places a first saw blade 2 on the workpiece support 14 in the position shown at the bottom in FIG. 2. The central opening finds its way onto the mandrel 22 with restricted play, on which the saw blade 2 is therefore seated in a freely rotatable manner. The workpiece support 14 then rotates on by 120° around the axis of rotation 18, so that the saw blade 2 is transported into the first processing station 11 and finds its way between the jaws of the arresting device 53. With the pin 55 the positioning device 51, formed by the separating fingers, now engages a first tooth space and brings a first tooth into the processing position. Now the arresting device 53 closes and clamps the tooth of the saw blade 2 to be processed firmly in relation to the grinding head 37. The latter can now grind the tooth back. When this is finished, the arresting device 53 opens and the positioning device 51 moves the saw blade 2 forward by one tooth. In this way all tooth backs 5 of all teeth of the saw blade 2 are processed one after the other.

[0040] When processing is finished, the workpiece support 14 rotates by 120°, so that the saw blade 2, whose tooth backs 5 have already been processed, finds its way into the grinding station 12. Processing of the tooth flanks now takes place here, again tooth after tooth. In the course of transferring the saw blade 2 from the grinding station 11 into the grinding station 12, the workpiece support 14 has guided a further, not yet worked saw blade 2 into the grinding station 11. While the desired tooth grinding is performed on the previous saw blade 2 in the processing station 12, grinding of the tooth backs takes place in the grinding station 11.

[0041] Both grinding stations 11, 12 operate synchronously with each other as a whole. But the grinding times of one individual grinding operation of a tooth in the grinding stations 11, 12 can be different. For example, it is possible to grind all tooth backs one after the other in the grinding station 11, while the upper tooth flanks of only the even-numbered teeth, and the lower tooth flanks of only the odd-numbered teeth are ground in the grinding station 12, so that the progression of the individual saw blades 2 in the grinding stations 11 and 12 takes place at different times and at different step lengths. However, this is not mandatory, both stations can also operate completely synchronously.

[0042] The positioning of the saw blades 2 in the processing stations 11, 12 is relatively independent of the exact positioning of the workpiece support 14 because of the assignment of the positioning device 51, 52, as well as the arresting devices 53, 54 to the respective grinding stations 11, 12. Furthermore, decoupling of the processing of the two saw blades 2 from each other takes place in this way. In particular, the interference with the work process on one saw blade by the work process on another saw blade, for example by the transmission of vibrations via the workpiece support 14, is unlikely, if not impossible.

[0043] The grinding machine 1 is designed as a multi-station grinding machine, which has two complete grinding stations 11, 12. The grinding stations 11, 12 have grinding heads, which can be moved by means of appropriate positioning devices, for example compound table arrangements 35, 36 and/or pivot tables 33, 34, in relation to the saw blade 2. Positioning devices 51, 52 and arresting devices 53, 54 for the workpiece are furthermore parts of the grinding stations 11, 12. The workpiece support 14 is used for positioning the saw blades 2 to the extent that their center axis is to be fixed in the grinding stations 11, 12. The rotation of the saw blades 2 around this center axis M, and the clamping in place of the saw blade in the respective rotated position for performing the grinding operation is the task of the respective units in the grinding stations 11, 12.

[0044] If required, the grinding machine can also have three grinding stations with 90° spacing and a four-armed workpiece support. For example, the third grinding station can be used for grinding the tooth face. If desired, the grinding machine can also perform additional manufacturing steps. For example, in place of one grinding station, or in addition to the existing grinding stations, it can be possible to provide a soldering station, which is arranged at the same angular spacing as the grinding stations among each other. The soldering station can be used for fastening hard metal plates on the teeth 3.

[0045] A very rapid and precise, and therefore cost-effective, processing of saw blades is possible by means of a grinding machine designed in this way. The grinding machine 1 is particularly suited for sharpening saw blades in the course of their manufacture. 

1. A grinding machine (1), in particular for saw blades (2), having a workpiece support (14) arranged for the simultaneous reception of several identical workpieces (2), a positioning unit (19) connected with the workpiece support (14), which is used to move the workpiece support (14) in steps and to maintain it in preselected positions, at least two grinding stations (11, 12), each of which has at least a. a grinding device (41, 42) for processing at least one surface (5, 6, 7) of the workpiece (2) which is fixed in place, b. a positioning device (51, 52) for positioning the workpiece (2) in the processing station (11, 12), and c. an arresting device (53, 54) for the temporary clamping of the workpiece (2) in the processing station (11, 12).
 2. The grinding machine in accordance with claim 1, characterized in that each processing station (11, 12) is equipped to process only one surface (5), or only one group of surfaces (6, 7), of all sawteeth (3) of the saw blade (2) located in the processing station.
 3. The grinding machine in accordance with claim 1, characterized in that the grinding device (41) has a grinding head (37) which is designed for processing one surface of a sawtooth (3).
 4. The grinding machine in accordance with claim 3, characterized in that the grinding head (37) is equipped for processing a tooth surface constituting a tooth back (5).
 5. The grinding machine in accordance with claim 1, characterized in that the grinding device (42) has at least one grinding head (38, 39), which is equipped for processing two tooth surfaces which are located opposite each other, and that these tooth surfaces constitute tooth flanks (6, 7).
 6. The grinding machine in accordance with claim 5, characterized in that the grinding heads (38, 39) can be simultaneously brought into engagement with the sawtooth (3).
 7. The grinding machine in accordance with claim 1, characterized in that each grinding station (11, 12) has a frame (31, 32) which supports the grinding device (41), the positioning device (51, 52) and the arresting device (53, 54).
 8. The grinding machine in accordance with claim 7, characterized in that the grinding machine (1) has a base frame (48), which supports the frames (31, 32) of the grinding stations (11, 12), and the positioning unit (19) for the workpiece support (14).
 9. The grinding machine in accordance with claim 1, characterized in that the grinding stations (11, 12) are arranged and designed in such a way that their grinding devices (37, 38, 39) can be simultaneously operated.
 10. The grinding machine in accordance with claim 1, characterized in that the grinding head (37, 38, 39), as well as positioning, guidance and displacement devices (33, 35, 34, 36), are part of the grinding devices (41, 42) in order to move each respective grinding head (37, 38, 39) in at least three spatial directions (X, Y, Z), which extend at right angles to each other, and in a pivot direction (B), which is aligned parallel with the axis of rotation of the saw blade (2).
 11. The grinding machine in accordance with claim 1, characterized in that the workpiece support (14) has receivers (21) for the freely rotatable seating of the saw blades (2).
 12. The grinding machine in accordance with claim 11, characterized in that the workpiece support (14) is embodied with three or more arms, and has at least one receiver (21) on each arm (15, 16, 17).
 13. The grinding machine in accordance with claim 11, characterized in that the receiver (21) is formed by a mandrel (22), whose radial distance in relation to the axis of rotation (18) of the workpiece support (14) is arranged to be adjustable.
 14. The grinding machine in accordance with claim 13, characterized in that several predetermined positions are assigned. to each mandrel. 